Major research activities during this reporting period include: (1) ongoing development of an ultrafast time-resolved laser spectroscopy laboratory; (2) time-resolved x-ray crystallographic studies of structural dynamics in proteins; and (3) giving invited lectures at national and international symposia as well as serving on scientific committees. We are developing the laser-based technology required to pursue time-resolved spectroscopic studies of protein dynamics from 100 fs to milliseconds using wavelengths ranging from the uv to the infrared. Some of the opportunities afforded by ultrafast spectroscopic methods have been published recently in two papers appearing in the Proceedings of the National Academy of Science. Ultrafast time-resolved laser spectroscopy requires mastery of many skills that traditionally arise from extensive hands-on experience. To shift the focus away from the technological demands and onto the protein systems of interest, we are developing computerized controls to optimize and control an ultrafast laser spectrometer. This effort will significantly enhance the quality and reproducibility of time-resolved spectra and will provide much greater flexibility in terms of accessible wavelengths. The infrastructure for implementing these controls is now largely in place and cutting-edge spectroscopic measurements should become nearly routine in the coming year. A multinational collaboration has been cultivated to pursue time-resolved structural studies of photoactive yellow protein (PYP) and myoglobin (Mb) using the technique of time- resolved x-ray crystallography. To date, diffraction data have been collected at the ESRF in Grenoble, France on both PYP and Mb with time resolution as fast as 150 ps. These data are currently being processed by collaborators, and results are expected in the coming few months. The PI has given invited scientific talks at two European Workshops, three U.S.-based international meetings, at Caltech, and at a DOE Workshop. The PI has also served on the Organizing Committee for the 1999 German-American Frontiers of Science Symposium and as a discussion leader for a Workshop on the Scientific Applications of the LCLS. - time-resolved spectroscopy ligand dynamics protein biophysics time- resolved x-ray crystallography heme proteins